The use of aqueous polyvinyl ester dispersions as adhesives is known. One disadvantage of these dispersions is their low resistance to water due to the presence of protective colloids, such as, for example, polyvinyl alcohol. U.S. Pat. No. 4,118,357 (DE-A2,620,738) describes the use of polyvinyl ester dispersions in which the polyvinyl ester component is grafted onto polyvinyl alcohol and which contain water-soluble acids or water-soluble acid metal salts as a hardener additive, to improve their resistance to water. With the addition of water-soluble acids as hardeners, these dispersions have an acceptable storage stability, (pot lives of more than 4 weeks); however, their resistance to hot water is unsatisfactory in comparison with the addition of water-soluble metal salts as hardeners. If the above mentioned metal salts are employed as the hardener additive together with the vinyl ester graft copolymer dispersions, the resultant adhesives have outstanding resistance to hot water; however, the storage stability is drastically reduced (pot lives of significantly less than 4 weeks).
Therefore, it is an object of the present invention to provide adhesives containing aqueous vinyl ester graft copolymers which, when mixed with water-soluble metal salt hardeners, have a high resistance to hot water and high storage stability.